roberts



Dec. 1, 1931.

D. B. ROBERTS OIL BURNER Filed Jan. 21, 1928 Patented Dec. 1, 1931UNITED STATES DAVID B. ROBERTS, or HARTFORD, coNNEcrIcU'r OIL BURNERApplication filed January 21, 1928. Serial No. 248,483.

Automatic oil burners, especially but not exclusively of the typeadapted for household use, are usually operated intermittently by anelectric motor. This motor is so-controlled as to start and stopautomatically and only when the motor is running is there anycombustible mixture delivered to the fire box. This means that the firegoes out completely during the period of stoppage and there thereforemust be some means provided to ignite the fuel when the motor starts.

This is usually done either by the use of a gas pilot flame or byelectrical means such as the producing of a spark in a spark plug. Theelectrical means is preferable to the gas means as there is alreadyelectrical current supplied to operate the motor and it is therefore notnecessary to do any piping as for as. a The main difliculty withelectric ignition has been a tendency of the spark plug electrodes tocorrode or become dirty, both thru the action of the electric arc andthru the deposit of carbon from the combustion. of the fuel. It has alsobeen difiicult to produce a spark hot enough and large enough to ignitethe fuel without excessive current consumption. A third difliculty liesin the fact that there is one particular position with reference to thedischarge nozzle in which the ignition means should be placed to producethe best results. Owing to the difierent sizes and types of furnaces inwhich such oil burners are placed it is generally necessary to makeadjustments of the'nozzle position while installing and with the sparkplug where electrical ignition means are separate from the nozzle italso necessitates adjustment of the ignition and due to lack of skill ininstalla- 40 tion the best possible position for the ignition is notusually obtained.

My invention consists in an improved method of electric ignitionwhereby,

1st. The electrodes, particularly the negative electrode, which Is theone which gets foul, is self-cleansing and provides an infinite numberof spark points instead of one point as in the ordinary type of sparkplug.

2nd. By the peculiarity of its construction provides for drawing out theelectric arc and making what virtually amounts to a flaming arc.

3rd. Provides a positive location for the electrodes in relation to thefuel discharge nozzle.

My invention is described in the following drawings which form a part ofthis specificat on but it is understood that I do not limit myself tothe specific construction shown.

In the drawings,

Fig. 1 is a front elevation in vertical section with parts in elevationof a boiler and oil burning unit.

Fig. 2 a plan view of one type of disc 65 electrode.

Fig. 3 a planview of another type of disc electrode.

Referring to the drawings the pump unit 1s sup-ported by springs 11 onbase plate 70 12 which is inserted in the ash pit 13 of the furnace. Thebase plate 12 also supports by means of adjustable legs 14 the plate 15which is located between the fire box 16 of the furnace and the ash pitl3 and which serves as a 70 support for building up a fire clayretaining wall 17 Plate 15 also supports a number of plates 18 soarranged as to ermit the free passage of air from the ash pit to the.fire box and at the same time provide a baflie prevent- 8 ing the flamefrom the fire box passing down into the ash pit.

The pump unit 10 has as a bottom plate the oil reservoir 19 to which themixture of oil and air is pumped by the spiral gears 20 and 21 which inturn suck the oil and air mixture from a carburetor, which, as it formsno part of the claim, is not shown. The top plate 22, see Fig. 1, of thepump unit 10 supports a motor 220 which has for an armature shaft ahollow shaft 23 to one end of which is keyed the pump driving gear 20.Telescopically arranged in the hollow shaft 23 is a tube 24 which may beadjusted for height and clamped in the desired position by clamp nut 25.The combustion mixture is forced by pressure by the pump from chamber 19up thru hollow shaft 23 and tube 24 to nozzle 26 where it escapes in theform of a spray thru port 27.

Permanently fixed to tube 24 by means of nozzle 26 and nut 28 iselectrode disc 29 which by its location is permanently fixed at adefinite distance from nozzle ports 27, and as tube 24 and nozzle 26revolve with the motor shaft disc 29 also revolves with them. This discmay be either of a smooth periphery as shown in Figure 4 or may have itsperiphery serrated as shown in Figure 5. Located at the pro-per distancefrom the disc 29 is electrode 30 which is supported by rod 31 which isthreaded into stud 32 inclosed in insulating cylinder 33 which isclamped to leg 14:. Fastened to stud 32 by binding post 35 is the wire34 from the source of electric supply, the other wire of the circuitbeing grounded by binding post 36 to motor frame 22. This circuit closeswhen the motor starts and opens after it has run a certain length oftime, but as this thermal relay does not form any part of my claim nofurther description is appended.

The operation is as follows: When the motor starts tube 24 is revolvedand a combustible mixture of oil and air is forced out thru nozzle 26into the fire box 16. At the same time current is supplied to electrode30 and jumps to disc 29 which as it is rapidly revolving draws out thespark into a flaming arc and ignites the mixture. Current is thenautomatically shut ofi from electrode 30. The revolving disc 29 not onlypresents an infinite number of points for formation of the are and drawsout the are into a flame but also by means of its rotary motion cleansesitself.

I therefore claim:

In an electric ignition for oil burners, the

combination of a fixed electrode, a rotating nozzle tube, a nozzle, adisc electrode fastened to said nozzle tube in a definite and ermanentrelation to the nozzle opening, lncluding a hollow shaft to rotate thenozzle tube, a pump connected to one end of said shaft and means foradjustably locating said nozzle tube in said shaft.

In testimony whereof I here-unto afix my signature.

DAVID B. ROBERTS.

